Electrical reactors



Sept. 12, 1967 D 'WA| E ET AL ELECTRICAL REACTORS Filed May 19. 1965United States Patent 3,341,793 ELECTRICAL REACTORS George David Wale,George Denis Antippa, and John Thomas Wilkins, Stafford, England,assignors to The English Electric Company Limited, London, England, aBritish company Filed May 19, 1965, Ser. No. 457,109 Claims priority,application Great Britain, May 25, 1964, 21,485/ 64 1 Claim. (Cl.336-84) This invention relates to electrical reactors.

According to the invention an electrical reactor comprises agenerally'rectangular laminated magnetic shield having two side membersand first and second transverse members arranged to provide a closedmagnetic circuit, at least the first transverse member being formed ofat least two parts spaced end to end and defining a gap therebetween, anon-magnetic support member formed with two end surfaces and extendingbetween the two transverse members, clamping means for causing thetransverse members to abut against the end surfaces of the supportmember, the said gap being positioned adjacent the associated end of thesupport member and the clamping means being effective to clamp thesupport members firmly between the second transverse member and both thesaid parts of the first transverse member, and an electrical windingdisposed about the support member.

In order that the invention may be more clearly understood a reactor inaccordance with the invention will now be described, by way of example,with reference to the accompanying drawing, in which:

FIG. 1 is a part-sectional plan view of the reactor, and,

FIG. 2 is a cross-sectional side elevation of the reactor on the lineA-A of FIG. 1.

In the drawing the reactor is shown as having a cylindrical windingwhich has a central aperture 12, and the winding is disposed within ashell-type magnetic shield generally indicated at 13. The shield is madeup of magnetic laminations as indicated at 14 in FIG. 1, and theselaminations are disposed in four similar spaced assemblies of top,bottom, and two side magnetic members as seen in the drawing.

Each such assembly is arranged in the form of a hollow rectangularstructure, and the four assemblies together also form a hollowrectangular structure.

One such assembly, shown generally at 16, comprises side magneticmembers and 21, bottom magnetic member 22, and top magnetic member 23,the latter member comprising two portions 23A and 23B separated by a gap24 which may include insulation if desired. The other three rectangularassemblies generally denoted by reference numerals 15, 17 and 18, aresimilar to the assembly 16 and each have a gap 24 between the twoportions of their top member.

The four similar rectangular magnetic assemblies 15 to 18 are spacedapart from one another by rectangular electrically insulating spacersgenerally indicated at 32, 33 and 34, each spacer comprising four spacermembers which have tongued ends and which are preferably made of wood.

Adjacent each major face of the reactor shield is disdosed one of twosteel clamping frames as shown at 31 and 35.

The whole shield comprising the four magnetic assemblies, the spacersand the clamping frames are bolted together by a number of bolts andnuts as for example shown at 36 and 37 in FIG. 1. The shield or any partthereof may of course be bonded or banded together by 3,341,793 PatentedSept. 12, 1967 any method known for the construction of laminatedmagnetic assemblies.

Disposed within the central aperture of the winding 10 is a stiffeningand support member shown generally at 40 and composed of electricallyinsulating non-magnetic material. This support member is built up of anumber of layers of such material, as shown, for example, at 43 and 44of FIG. 1.

The two ends of the member 40 do not extend over sufficient of the innerfaces of the top members to provide a sufficient support for the topmembers of the rectangular assemblies 15 and 18. To increase the supportplate structures 45 are provided at the top and bottom of the reactorshield. These are each shown in the drawing to comprise a metal assemblyof inverted channel sections 46 and stiffening pieces 47 welded to afiat metal plate 48. To provide insulation between the plate structures45 and the laminations 14 against which they lie, sheets of electricalinsulation 49 are provided which overlap the plates 48 all around theirperimeters.

The top plate structure 45 is attached to the top of the frames 31 and35 by bolts 50 and nuts 51. In a similar manner the bottom platestructure 45 is attached to the bottom of the frames 31 and 35.

The plate structures 45 are further secured to the shield by bolts andnuts as shown for example at 53 and 54 in the drawing. The bolts 53extend through the member 40 and therefore also serve to clamp the topand bottom members of the hollow rectangular structure against themember 40. The bolts are electrically insulating and preferably compriseglass fibre resin impregnated rods having metal fittings at either endto provide sufficient strength of the screw threads which engage thenuts 54 The stiffening and support member 40 may be of any suitableinsulating and non-magnetic material but is preferably of densifiedwood. Its prime object is to provide stiffening and support between thetop and bottom members and so to reduce any elastic deflection thereofdue to the alternating magnetic forces set up in the shield. Theseforces have twice the frequency of the alternating current in thewinding and attract the top and bottom magnetic members of the magneticshield inwardly together. By reducing movement of the shield the noiseemitted by the reactor is decreased.

The two-part arrangement of the top magnetic members also ensures thatthe stiffening and support member 40 can always be firmly clampedbetween the top and bottom members as this two-part arrangement allowsfor minor variation in the dimensions of the members. If desired themagnetic shield may be further sub-divided with gaps such as 24 providedin the bottom members and additionally or alternatively with gapsprovided in the side members. If desirable more than one gap may beprovided in each magnetic member of the shield, such gaps for the topand bottom members being preferably within those parts of the shieldwhich lie wholly or partly against the ends of the stiffening andsupport member 40.

Further, the provision of the member 40 and the twopart arrangement ofthe top and bottom magnetic members with the gaps 24 enables the reactorparts to be proportioned so that they are less likely to be excited toresonance by the magnetic forces set up in the shield so that thepossibility of the shield resonating under operating conditions, withresultant increased noise emission, is reduced.

It is not essential that the top and bottom magnetic members be clampedagainst the stiffening and support member 40 by bolts as shown, anyother suitable means may be used.

If desired the reactor may be arranged with the winding and stiffeningand support member horizontal. For this arrangement the magnetic membersdescribed in the specification as top and bottom become side members,and members described as side members become top or bottom members.

What we claim as our invention and desire to secure by Letters Patentis:

An electrical reactor comprising a generally rectangular laminatedmagnetic shield having two side members and first and second transversemembers arranged to provide a closed magnetic circuit, at least thefirst transverse member being formed of at least two parts spaced end toend and defining a gap therebetween, a non-magnetic support memberformed with two end surfaces and extending between the two transversemembers, clamping means for causing the transverse members to abutagainst the end surfaces of the support member, the said gap beingpositioned adjacent the associated end of the support member and theclamping means being effective to clamp the support member firmlybetween the second transverse member and both the said parts of thefirst transverse member, and an electrical winding disposed about thesupport member.

References Cited UNITED STATES PATENTS 2,445,408 7/1948 Root 336-178 X2,658,113 11/1953 Holmes -a 336-178 X 2,909,742 12/1959 Lambertson336-210 X 2,892,169 6/1959 Teague et a1 336219 X 3,195,082 7/1965Weatherill et a1. 336210 X 3,195,087 7/1965 Welch 33621O X 3,241,0483/1966 Lee 336-215 X LEWIS H. MYERS, Primary Examiner.

T. I. KOZMA, Assistant Examiner.

